Latency for facultative expression of male-typical courtship behaviour by female bluehead wrasses depends on social rank: The ‘priming/gating’ hypothesis

Abstract

Although socially controlled sex transformation in fishes is well established, the underlying mechanisms are not well understood. Particularly enigmatic is behavioural transformation, in which fish can rapidly switch from exhibiting female to male-typical courtship behaviours following removal of 'supermales'. Bluehead wrasses are a model system for investigating environmental control of sex determination, particularly the social control of sex transformation. Here, we show that the onset of this behavioural transformation was delayed in females that occupied low-ranking positions in the female dominance hierarchy. We also establish that expression of maletypical courtship behaviours in competent initial-phase (IP) females is facultative and gated by the presence of terminal-phase (TP) males. Dominant females displayed reliable TP male-typical courtship behaviours within approximately 2 days of the removal of a TP male; immediately following reintroduction of the TP male, however, females reverted back to female-typical behaviours. These results demonstrate a remarkable plasticity of sexual behaviour and support a 'priming/gating' hypothesis for the control of behavioural transformation in bluehead wrasses.

Let's talk about sex: Mechanisms of neural sexual differentiation in Bilateria

“…In many species, behavioral sex transition is observed before any changes in circulating hormones are detected (DeAngelis et al, 2018; Dodd et al, 2019; Price et al, 2018). This observation leads to the model that sex change is initiated by the brain of sequential hermaphrodites due to the role it plays in interpreting and reacting to the social environment.…”